Intrepid - breathable waterproof membrane
Based on both Trenchant Textiles own testing and the feedback of materials professionals given the chance to preview Intrepid, Trenchant Textiles believes it to be the lightest and most breathable waterproof membrane on the market.
The key to Intrepid's performance is its pores, their size, their shape, their uniformity, the materials that they're made out of, and ultimately, the fact that they contribute roughly 74% of the membrane by volume. The membrane's pores are created through a patented process which leverages polypropylene's unique molecular properties – properties which make possible the creation of very smooth, spherical pores. Beyond just making tidy pores though, polypropylene is an ideal material for a waterproof-breathable membrane because it is highly hydrophobic, the result of its low surface energy. Liquid water is thus repelled by the matrix structure of polypropylene. Where water is pressed against a pore though, it intrudes slightly but is held contiguous in the form hemispherical lumps by surface tension, thus preventing the water from permeating the membrane. PTFE is also naturally hydrophobic – even more so than than polypropylene in fact, with a surface energy roughly 20% lower.
However, the ability of a porous, hydrophobic membrane to repel water is a function of not only hydrophobicity, but also of the size and shape of its pores. Not surprisingly, round pores are much more effective, as water in ball form maintains its integrity more easily than in triangular or trapezoidal shapes. This is where PTFE and electro-spun PU membranes are challenged. Jagged, triangular voids do a poor job of creating surface tension. This is the same reason why Loofah sponges are not much good at soaking up spills. In addition to being of a preferred shape, the Intrepid membrane's pores are also of a preferred size – smaller. Much smaller. Whereas the leading maker of ePTFE membranes puts their mean pore size at roughly 200 nanometers, Intrepid's pores are roughly a tenth that size. While this makes no difference to water vapor, it makes a huge difference to water droplets.
The Intrepid membrane can be laminated to polypropylene fabrics and paired with polypropylene trim to make garments that are 100% recyclable, use no water in dyeing, and require far less DWR, due to polypropylene's strong inherent hydrophobia.